Font wheel aligning device



y 6, 1969 E. L. RAGLAND m, ETAL 3,442,365

FONT WHEEL ALIGNING DEVICE Filed Sept. 29, 1967 INVENTORS. EVAN LRAGLAND I[[ L BY CHARLES W. WIEDEMAN,\JR.

&1 M JW ATTORNEY United States Patent 3,442,365 FONT WHEEL ALIGNING DEVICE Evan L. Ragland III, Atherton, and Charles W. Wiedeman, Jr., Castro Valley, Calif-Z, assignors to Friden, Inc., a corporation of Delaware Filed Sept. 29, 1967, Ser. No. 671,704 Int. Cl. B41j N44 US. Cl. 197-53 3 Claims ABSTRACT OF THE DISCLOSURE Cross reference to related application The apparatus disclosed in this application includes mechanism disclosed in application Ser. No. 599,201, filed Dec. 5, 1966 by Louis C. Thayer and assigned to the same assignee as the present application.

Background: Field 0 the invention This invention relates to printing devices and in particular to on-the-fly printers having flexible font wheels.

Background: Prior art Printers for communications have used font wheels that were stopped for printing. Faster printers for higher communication speeds and for computers have used continuously-rotating font wheels for on-the-fly printing. But such wheels tend to smear the printed characters because the type faces are moving during the printing impact. One such font wheel is in the form of a disc with thin flexible spokes each carrying a type face on a character pad. This smearing and blurring of the printed letters limits the permissible speed.

Further, the print hammer, if it strikes slightly early or late, will cause the printed character to be misaligned, and if it is much too early or late, or fails to rebound, it will snag the spoked wheel.

Summary of the invention According to this invention a printer comprises a font wheel having slope-sided grooves on the backs of the flexibly-mounted character pads for controlling alignment of the printed characters. A toothed disc rotated with the font wheel prevents printing it the character pad is not near correct alignment when the high-speed hammer is operated. In this way, correct alignment is assured, and the type, while in actual printing contact with the paper, is substantially halted so that smearing of the impression is substantially obviated.

Brief description of the drawings The organization and method of operation of the invention may best be understood from the following description when read in connection with the accompanying drawings in which:

FIG. 1 is a perspective view of a printer incorporating the present invention;

FIG. 2 is a partial cross-sectional view of the printer shown in FIG. 1;

FIG. 3 is an enlarged fragmentary perspective view of the font wheel and the notched aligning disc of the present invention;

FIG. 4 is an enlarged fragmentary elevational view 3,442,365 Patented May 6, 1969 of the back of the font wheel and the aligning disc; and

FIG. 5 is an enlarged fragmentary plan view of the font wheel and aligning disc for showing the preferred construction thereof.

Description of a preferred embodiment In FIG. 1 there is shown a printer 10, without the usual cover. A carriage assembly 14, having a font wheel 16, a hammer control disc 18, and a print hammer assembly 20, is mounted on a frame 12 for straight line movement across the face of a sheet of paper 22. An inked ribbon 24 is shown, but other known inking devices may be used.

The frame 12 includes a base member 28 and spaced end plates 30 and 31 mounted in upstanding parallel relation to each other. A pair of spaced, parallel, carriagemounting rails 32 and 33 extend horizontal between the end plates 30 and 31 near the forward portion of the printer 10. Platen 26 extends parallel with the rails 32 and 33 and is rigidly attached to the end plates 30 and 31 rearward of the printer.

The carriage assembly 14 includes a pair of upstanding side plates 36 and 37. Each side plate has formed therein a pair of openings into which associated bearings, or bushings 39 and 40, are seen-red. The bearing 39 associated with each of the side plates 36 and 37 is in axial alignment and in sliding surrounding engagement with the upper rail 32. Likewise, the bearing 40 associated with each of the side plates 36 and 37 is in axial alignment and in sliding surrounding engagement with lower rail 33. In this manner the carriage assembly is mounted for easy movement in a straight line between end plates 30 and 31 and parallel with platen 26. Other well-known structures may be utilized to mount the carriage assembly for movement as described.

A carriage-assembly advancing means for sequentially stepping the carriage assembly 14 from left to right during the printing of a line, and for rapidly moving the carriage assembly back to its leftmost position, is shown in FIGS. 1 and 2 as including, for example, a cable 44 which is trained about an idle pulley 46 and a driving capstan 47, and connected to opposite side plates 36 and 37. The capstan 47 (FIG. 2) is coupled to a source of mechanical power 43, which may be any well-known spring or electric-motor-driven carriage-advancing mechanism.

The font wheel 16 is rotatably journalled in a mounting block 50 (FIG. 2) secured to a pair of arms '52 which extend rearward from respective side plates 36 and 37 of the carriage assembly 14. The font wheel 16, as partially illustrated in FIG. 4, comprises a radially inner central, or hub, portion 54 and a plurality of typecarrying spokes 56. Preferably, it is molded of nylon with glass reinforcing fibers. A power shaft 58 extends through the hub portion 54 of font wheel 16 (FIG. 2) and is fastened thereto as by means of a tapered pin passing through aligned apertures in the hub and shaft. The power shaft 58 is journalled in a bearing (not shown) Which is secured to the mounting block 50, and is connected to any suitable source to rotative power, such as a constant speed electric motor 60, through suitable gearing 62.

The distal, or outer, end of each spoke 56 is formed with a pad 57 that has a character type that faces the platen 26. Each pad 57 has a different character type thereon wherein a set, or font, of character types is formed which may be numeric symbols, or the alphabet plus numeric symbols, and other special symbols, such as punctuation marks, etc., as required.

The spokes 56 are formed or constructed so as to be flexible in the direction transverse to the plane of the wheel in order that they may be deflected from their normal plane when driven into printing contact with the inked ribbon 24 or paper 22. The spokes are also constructed so as to be flexible in the direction parallel to the plane of the wheel, to permit the character pad to be stopped during the printing impact although the rest of the font wheel continues to rotate. The spokes may be round in cross-section as shown at 55 in FIG. 3.

The print hammer assembly 20 includes an F-shaped hammer member 65 (FIG. 2) pivotally mounted in the carriage assembly 14, for movement in a plane normal to the plane of the font Wheel 16. The F-shaped hammer member 65 includes an upper arm 67 and a lower arm 69. The outer end of the upper arm 67 is formed to pro vide a nose, or hammer head 70, which is positioned just forward of the print position. A hammer actuating magnet 72 is mounted in the carriage assembly 14 at a position just forward of the lower arm 69. The hammer member 65 is biased in the counter-clockwise direction, as viewed in FIGS. 1 and 2, by a spring 74 so that, normally, the hammer head 70 is held out of contact with the font wheel, and the lower arm 69 is held spaced from the magnet 72. Upon application of an electric current pulse to the magnet, the hammer head 70 is driven clockwise against the back of the moving character pad 57. The spoke 56 flexes and lets the type be moved into printing contact with the inked ribbon 24 or paper 22.

One of the features of this invention is the prevention of smearing of the printed character. As shown in the drawings, the back side of each character pad 57 is provided with a shallow groove, or recess 76, that cooperates with the hammer head 70 to help align the character pad 57 in its proper print position even though the pad may vibrate, and even through the timing of the current pulse to the hammer magnet, and the speed of response of hammer 65 thereto may vary. The groove has a radius of about .078 inch and extends substantially the length of pad 57. The nose, or striking end of hammer head 70 has a slightly smaller radius so as to mate with the groove. If the hammer strikes the grooved pad in slight misalignment, the sloped side of the hammer nose abuts, or strikes, the sloped side of the groove to drive the character pad toward correct printing alignment as the pad is also forced toward the platen 26.

If the pad is early, the trailing slope of the groove abuts the hammer and stops against it. If the pad is late, the hammer first drives against the leading slope and then receives the impact of the trailing slope for stopping the pad. The stopped and aligned pad is then driven against the work. Thus the hammer nose 70 and the sloped sides of the groove 76 of the character pad constitute mutual abutments for the impact of the hammer and pad against each other.

Unavoidably, the type face stays in pressure contact with the ribbon or paper for a certain length of time, and the continuous rotation of the type wheel tends to slide the type during this contact. The flexibility of the spokes 56 permits the pads 57 to be stopped by the hammer and also to be slowed frictionally by the clamping force of the hammer impact. The sloped sides of the curved nose of the hammer head 70 and of the groove 76 in the pad constitute abutment faces which aid in stopping the pad during the printing impact.

The print hammer control disc 1-8 is fixed to the font wheel shaft 58 adjacent the forward side of the font wheel '16, and includes a rim of flange 78 having a plurality of cam teeth 81 with the intervening notches 80 aligned with the spokes '6 of the font wheel 16. The F-shaped hammer member 65 includes a second head 82 located below the hammer head 70 which cooperates with the cam teeth 81 in the rim of the control disc 18 for positively and mechanically preventing the hammer from striking between the character pads '57 and snagging them, in the event of faulty timing of the hammer strokes. The sloping sides of the teeth 81 insure the return of the hammer head 70 to its normal, inactive position for keeping it clear of the rotating font wheel. Thus, the teeth 81 and notches also aid in insuring proper alignment of the printed characters, restrict and partially guide the hammer as it enters the notches 80 during the printing stroke, to aid in the proper timing of the hammer relative to the character pads, and can also earn the hammer out of the notches 80.

There has been described a high-speed printing apparatus having a continuously rotatable font wheel which is constructed in a manner to align the characters in their proper printing position and to reduce vibration of the characters as they contact the inked ribbon or paper so as to substantially eliminate smearing of the printed characters.

While the principles of the invention have been made clear in the illustrative embodiment, there will be obvious to those skilled in the art many modifications in structure, arrangement, proportions, the elements, material and components, used in the practice of the invention, and otherwise, which are adapted for specific environments and operating requirements, without departing from these principles. The appended claims are, therefore, intended to cover and embrace any such modifications within the limits only of the true spirit and scope of the invention.

What is claimed is:

1. An apparatus for printing on a surface of a sheet of paper including:

'(a) a carriage assembly mounted for straight line movement across the face of the sheet of paper;

'(b) a rotatably mounted font wheel carried by said carriage assembly and having a plurality of flexibly mounted type-carrying pads;

(c) means for continuously rotating said font wheel;

(d) a hammer carried by said carriage assembly for selectively driving the type-carrying pads into contact with the surface of said sheet of paper; and

(e) a hammer control disc rotated with said continuously rotating font wheel and having a plurality of cam teeth aligned with spaces between the type-carrying pads for preventing operation of the hammer when misaligned with said pads, and for camming the hammer to aid its return motion away from said pads.

2. A printing apparatus as claimed in claim 1 further comprising:

means for aligning said type-carrying pads in printing position including an abutment on each pad for abutting the hammer to stop said flexibly-mounted pad.

3. A printing apparatus as claimed in claim 1 wherein said hammer control disc includes:

a rim portion having the cam teeth and notches formed therein for facilitating the alignment of said typecarrying pads with the hammer printing operations, and to prevent the hammer from striking between the pads of the rotating font wheel.

References Cited UNITED STATES PATENTS 1,453,867 5/1923 Fanslow 1976.4 1,601,896 10/1926 Welter l97-6.4 2,127,509 8/1938 Fuchs 19753 XR 2,236,663 4/1941 Adams 19753 3,157,264 11/1964 Frechette 19753 XR 3,289,805 '12/'1966 Kleinschmidt 197--'53 XR 3,307,672 3/1967 Young 19753 XR 3,310,147 3/ 1967 Clary et al 19755 3,356,199 12/1967 Robinson 19754 EDGAR S. BU'RR, Primary Examiner.

U.S. Cl. X.R. 19718, 49, 55 

